FreeCiv - Freeciv is an open-source, turn-based strategy game based on Civilization II.
Sins Of A Solar Empire - Sins of a Solar Empire is an Adventure, Strategy, Real-time-strategy, Science-fiction, Exploration, Aliens, Single and Multiplayer Space Simulation developed by Ironclad Games and published by Stardock.
Freeciv for Android - Port of Freeciv to Android - similar to Civilization series.
Stellaris - Stellaris is an Adventure-based, RTS (Real-time Strategy) Space, Sandbox, Sci-Fi, Single and Multiplayer video game created and published by Paradox Interactive.
Widelands - Widelands is a free, open source real-time strategy game with singleplayer campaigns and a...
FreeOrion - FreeOrion is a turn-based space empire and galactic conquest (4X) computer game being designed and...